Superconducting loop, saddle and birdcage MRI coils capable of simultaneously imaging small nonhuman animals

ABSTRACT

New MRI coil and resonators are disclosed based solely on superconducting inductive element and built-in capacitive elements as well as hybrid superconducting-metal inductive and capacitive elements having superior SNR. Single and multiple small animal MRI imaging units are also disclosed including one or more resonators of this invention surrounding one or more small animal cavities. Methods for making and using the MRI coils and/or arrays are also disclosed.

RELATED APPLICATIONS

The present application is the U.S. Nationalization of PCT/US2005/001813filed Jan. 20, 2005, which claims provisional priority to U.S.Provisional Patent Application Ser. No. 60/537,782 filed Jan. 20, 2004,the entire contents of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the general field of magneticresonance, and to methods and apparatus for their practice.

More particularly, the present invention relates to an apparatus and amethod for using the apparatus, where the apparatus includes a housingincluding at least one cavity for housing a small mammal, where thehousing includes a superconducting array of MRI elements cooled byliquid nitrogen and where the housing with an animal therein is designedto place in an MRI instrument and MRI images of the mammal obtained.

2. Description of the Related Art

It is known that in magnetic resonance imaging (MRI) when receivingsignal coil noise dominates, overall system noise, using superconductingreceiving coil, increases significantly as does overall signal-to-noiseratio of the MRI system. Superconducting coils in either surface coil orvolume coil configuration are formed out of four or more sections ofdielectric/superconductor or dielectric/metal strips. Strips are madeout of thin high temperature superconducting (HTS) or metal thin filmsdeposited on dielectric rigid or flexible substrates. Such strips areconnected together via build-in capacitors. At each of the connections,YBCO layers are separated by dielectric layers to form capacitors.Resonant frequency is determined mainly by a length of the structure anda thickness of the dielectric layer separating the YBCO layers and adielectric constant of the dielectric layer. Flat surface coils, saddlecoils and volume birdcage coils have been designed.

Birdcage radio frequency coils have been widely used in magneticresonance imaging because of their efficiency and azimuthal B1 fieldhomogeneity and design of all superconducting birdcage for small animalshas a practical potential. Thus, there is a need in the art forefficient small animal including small mammal MEI birdcage devices thathave low noise and/or improved signal-to-noise ratios and have thecapability of simultaneously housing multi-animals in a single device.

SUMMARY OF THE INVENTION

The present invention provides a MRI single coil including compositestructures of dielectric layers and superconducting layers and/ormetallic layers, where the layers are constructed to form inductiveregions of the superconducting layers and/or metallic layersinterconnected by capacitive regions formed by superconducting layersand/or metallic layer having a dielectric layer interposed therebetween.

The present invention provides a MRI phased array of coils of thisinvention constructed in such a way as to form MRI housings including asingle animal tube or multiple animal tubes, each tube having one ormore MRI arrays associated therewith.

The present invention also provides a multi-animal apparatus adapted forsimultaneous measurements of multi-animals, where the apparatus includesa plurality of animal tubes, each tube including one or more MRI coilsor coil arrays of this invention. In one preferred embodiment, eachanimal tube includes a birdcage-like MRI coil array. The apparatus alsoincludes a cryogenic system for cooling the MRI coils or MRI coilarrays.

The present invention also provides an MRI resonator apparatuscomprising four superconducting members, each member including asuperconducting layer, where the members arranged to form a closed shapehaving four overlapping regions, and separating dielectric layersinterposed between the superconducting layers at the overlapping regionsto form built-in capacitors. Each member comprises a substratedielectric layer upon which the superconducting layer was formed. Thesubstrate dielectric layers can be rigid. Two of the substratedielectric layers can be rigid and two of the substrate dielectriclayers can be flexible. The members are straight. Two of the members canbe straight and two of the members can be curvilinear. Two of themembers can be straight and two of the members can be arcuate. Thesubstrate dielectric layers can be the separating dielectric layers. Theapparatus can further comprise a metal layer formed on an exposedportion of a dielectric layer or a external dielectric layer formed formon an exposed portion of a superconducting layer with a metal layerformed on the outer surface of the external dielectric layer to formcoupling or decoupling capacitive elements. The apparatus can furthercomprise wires bonded to the metal layers, where the metal wires areadapted to link a plurality of the apparatus together to form arrays orto connect the apparatus to a pre-amplifier.

The present invention also provides a hybrid MRI resonator apparatuscomprising two superconducting members, each member including asuperconducting layer, two metal member, and separating dielectriclayers, where the superconducting members and the metal members arearranged to form a closed shape having four overlapping regions and theseparating dielectric layers are interposed between the superconductinglayers and the metal members at the overlapping regions to form built-incapacitors. Each superconducting member comprises a substrate dielectriclayer upon which the superconducting layer was formed. The substratedielectric layers can be rigid. Two of the substrate dielectric layerscan be rigid and two of the substrate dielectric layers can be flexible.The superconducting members can be straight or curvilinear or arcuate.The substrate dielectric layers can be the separating dielectric layers.The apparatus can further comprise a metal layer formed on an exposedportion of a dielectric layer or a external dielectric layer formed formon an exposed portion of a superconducting layer with a metal layerformed on the outer surface of the external dielectric layer to formcoupling or decoupling capacitive elements. The apparatus can furthercomprise wires bonded to the metal layers, where the metal wires areadapted to link a plurality of the apparatus together to form arrays orto connect the apparatus to a pre-amplifier.

The present invention provides a birdcage-type resonator apparatuscomprising a plurality of coils apparatus including four members, eachmember including a superconducting layer, where the members arranged toform a closed shape having four overlapping regions, and separatingdielectric layers interposed between the superconducting layers at theoverlapping regions to form built-in capacitors, and at least one smallanimal cavity, where the coil apparatus are arranged around the cavityto permit MRI imaging of an animal placed within the cavity. Each membercomprises a substrate dielectric layer upon which the superconductinglayer was formed. The substrate dielectric layers can be rigid. Two ofthe substrate dielectric layers can be rigid and two of the substratedielectric layers can be flexible. The members can be straight. Two ofthe members can be straight and two of the members can be curvilinear.Two of the members can be straight and two of the members can bearcuate. The substrate dielectric layers can be the separatingdielectric layers. The apparatus further comprises a metal layer formedon an exposed portion of a dielectric layer or a external dielectriclayer formed form on an exposed portion of a superconducting layer witha metal layer formed on the outer surface of the external dielectriclayer to form coupling or decoupling capacitive elements. The apparatusfurther comprises wires bonded to the metal layers, where the metalwires are adapted to link a plurality of the apparatus together to formarrays or to connect the apparatus to a pre-amplifier.

The present invention also provides a birdcage-type resonator apparatuscomprising a plurality of coils apparatus including two superconductingmembers, each member including a superconducting layer, two metalmember, and separating dielectric layers, and at least one small animalcavity, where the coil apparatus are arranged around the cavity topermit MRI imaging of an animal placed within the cavity and where thesuperconducting members and the metal member are arranged to form aclosed shape having four overlapping regions and the separatingdielectric layers are interposed between the superconducting layers andthe metal members at the overlapping regions to form built-incapacitors. Each superconducting member comprises a substrate dielectriclayer upon which the superconducting layer was formed. The substratedielectric layers can be rigid. Two of the substrate dielectric layerscan be rigid and two of the substrate dielectric layers can be flexible.The superconducting members can be straight. The superconducting memberscan be curvilinear. The superconducting members can be arcuate. Thesubstrate dielectric layers can be the separating dielectric layers. Theapparatus further comprises a metal layer formed on an exposed portionof a dielectric layer or a external dielectric layer formed form on anexposed portion of a superconducting layer with a metal layer formed onthe outer surface of the external dielectric layer to form coupling ordecoupling capacitive elements. The apparatus further comprises wiresbonded to the metal layers, where the metal wires are adapted to link aplurality of the apparatus together to form arrays or to connect theapparatus to a pre-amplifier.

The present invention also provides a small animal MRI apparatuscomprising a vacuum housing including at least one cylindrical cavityadapted to receive a small animal, a coolant reservoir including acoolant, a coolant inlet, a coolant outlet and a cold plate forming aninternal end of the reservoir, a resonator of this invention surroundingeach cavity or a plurality of coils of this invention positioned withinthe housing to permit MRI imaging of an animal in each of the cavities.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention can be better understood with reference to the followingdetailed description together with the appended illustrative drawings inwhich like elements are numbered the same:

FIGS. 1A-K depict two different loop detector elements of thisinvention, a fabrication method, expanded views of portions of thestructure showing built in capacitors and a corresponding circuitdiagram;

FIGS. 2A & B depict a single saddle loop or coil (A) of this inventionand a tube made by placing mating saddles together (B);

FIGS. 3A & B depict a preferred embodiment of birdcage type MRI coilarray of this invention;

FIGS. 3C & D depict another preferred embodiment of birdcage type MRIcoil array of this invention;

FIGS. 4A & B depict a preferred embodiment of a mixedmetal/superconductor MRI resonator of this invention;

FIGS. 4C & D depict another preferred embodiment of a mixedmetal/superconductor MRI resonator of this invention;

FIG. 4E depicts a schematic diagrams corresponding to the resonators ofFIGS. 4A-D;

FIGS. 5A & B depict a preferred birdcage-type hybrid coil arrayresonator of this invention;

FIGS. 5C-E depict another preferred birdcage-type hybrid coil arrayresonator of this invention;

FIGS. 6A & B depict another preferred birdcage-type hybrid coil arrayresonator of this invention;

FIGS. 7A & B depict another preferred birdcage-type hybrid coil arrayresonator of this invention;

FIGS. 8A & B depict a preferred small animal MRI apparatus of thisinvention;

FIG. 9 depicts another preferred small animal MRI apparatus of thisinvention;

FIG. 10 depicts another preferred small animal MRI apparatus of thisinvention; and

FIGS. 11A-D depict physical characteristics of the coils resonators ofthis invention.

FIG. 12A depicts performance of a circuit having the tuning and matchingcircuitry within the small animal device and cooled simultaneouslyproducing improved SNR.

FIG. 12B depicts the tuning and matching circuitry for use with thecoils and arrays of this invention.

DETAILED DESCRIPTION OF THE INVENTION

The inventors have discovered that a new small animal or multi-smallanimal MRI apparatus can be designed that has an improvedsignal-to-noise ratio. The apparatus includes one or more small animaltubes designed to receive a small animal and at least one MRI coil orcoil array associated therewith each tube. In one preferred embodiment,the coils or coil arrays are fabricated solely from superconductingmaterials and dielectric materials. In another preferred embodiment, thecoils or coil arrays are fabricated from superconducting materials,metallic conducting materials and dielectric materials. The apparatusesalso include a cryogenic cooling system. The multi-animal versions ofthese apparatus provide improved MRI images simultaneously for all theanimals within the multiple animal apparatus.

The present invention broadly relates to an MRI coil or an array of MRIcoils. Each coil includes a plurality of inductive elements, where eachinductive element is formed of a superconducting layer deposited on adielectric substrate or a metallic conducting layer or member. Each coilalso includes an equal plurality of built-in capacitive elementsinterconnecting adjacent pairs of the inductive elements, where eachcapacitive element is formed from two superconducting layers with adielectric layer interposed therebetween or a superconducting layer anda metallic conducting layer with a dielectric layer interposedtherebetween. The coils can be rectangular in shape, circular in shapeor elliptical in shape and can be flat, curved or curvilinear.

The present invention also broadly relates to a small animal MRIapparatus including at least one small animal cavity or tube designed toreceive a small animal. Each tube includes an effective number of MRIcoils or coil arrays sufficient to provide adequate MRI data about theanimal or animals in the apparatus. The apparatus also includes acryogenic cooling unit for maintaining each coil or array in asuperconducting condition. The apparatus preferably includes multiplecavities, each cavity with coils or arrays so MRI data can be acquiredfrom each animal simultaneously.

The present invention also broadly relates to method for acquiring MRIdata on multiple small animals including the step of placing one or moresmall animals in the multiple small animal apparatus of this invention.After placing the animals in the apparatus, the small animal MRIapparatus is positioned within an MRI apparatus. The MRI coils or arrayswithin the apparatus are then Cooled to a superconducting state. MRIdata is then collected simultaneously from each of the animals in theapparatus.

A significant improvement of the signal-to-noise ratio (SNR) formagnetic resonance imaging (MRI) applications, in which the thermalnoiśe of the rf receiver probe dominates the system noise, can beachieved either by cooling a normal metal probe or by usingsuperconductors. The noise in an MRI system is primarily due to thermalnoise in the receiver coil and body, which is described by the Nyquistformula: V_(n)=4k(T_(b)R_(b)+T_(c)R_(c))Δf, where k is Boltzman'sconstant, T_(b) and T_(c) represent the body and coil temperatures,respectively, and Δf is the bandwidth of the receiver.

MRI is a widely used diagnostic tool, that provides unsurpassed abilityto image soft tissue. In MRI, the subject is placed in a dc magneticfield, a sequence of magnetic field gradients and rf excitation pulsesare then applied to the subject, and relaxing nuclei (usually protons)produce weak decaying rf signals that are detected by an rf receiverprobe. Such signals are weak due to the small differences in energylevel populations of parallel and anti-parallel spins nuclei, (about 6ppm at 1.5 T) that contribute to the signal. In both research andclinical MRI, there is a need for high resolution and/or fast scanimaging, and the signal-to-noise ratio (SNR) is the main limitation onfulfilling these requirements. This makes the overall SNR the mostimportant parameter of MRI systems.

Noise in the system, in general, is created by conductive losses in theprobe and in the body. There are two regimes of such conductive lossesin MRI system. In the first regime, the loss in the body dominates, sothe SNR is primarily body loss dependent. While, in the second regime,the loss in the coil dominates, so the SNR is primarily coil lossdependent. In the body-loss dependent regime, there is little advantagein reducing ohmic coil loss. However, in the coil loss dependent regime,it has long been recognized that cooling the probe reduces coil noise,and, therefore, can significantly increase the SNR of the measurements.

The discovery and development of high-temperature superconducting (HTS)materials has resulted in several attempts to build practical probeswith improved SNR. Indeed, preliminary studies have shown that forselected applications, where the MRI system noise is in the coil lossregime (low-field MRI, high-field microscopy, and small-volume MRI), HTSMRI receiver coils perform significantly better than comparable coppercoils. HTS thin films are very attractive for use in surface receivercoils, because such films at 77 K exhibit an extremely low surfaceresistance Rs (about 150 μW at 10 MHz). This low surface resistance isseveral orders of magnitude lower than the surface resistance of copperat the same frequency and temperature. In addition, HTS materials haverelatively high critical temperature which can simplify cryostat designand affords for a short distance between the superconducting coil andthe body or body part of the imaged.

One limitation when using surface probes for human imaging is theirrelatively small field of view. As previously mentioned, phased arrayscan be used to allow small coils to cover a large region of interest,while preserving the improved SNR. Recently, the use of arrays has beencomplemented by elucidating optimal data combinations. For example, aset of weighting coefficients are derived, by which each pixel of eachimage is weighted in order to achieve an optimal combination. The limitof operation may not be defined solely by SNR, but may also havecontributions from the time available for image acquisition in suchtechniques as functional brain imaging, real-time cardiac MRI, andpediatric MRI.

Until recently, increases in MRI acquisition speed was limited by thespeed at which the field gradients could switched. However, the hardwarespeed has increased to the point where the main limitations are nowphysiological. Faster gradient switching used for imaging and/orapplying more rf power per unit time cause nerve stimulation andheating, respectively. To overcome these limitations, two newtechniques, known as SMASH (SiMultaneous Acquisition of SpatialHarmonics) (see D. K. Sodickson, W. J. Manning, “Simultaneousacquisition of spatial harmonics (SMASH); fast imaging with rf coils,”Magn. Reson. Med. vol. 38, pp. 591-603, 1997) and SENSE (SENSitivityEncoding) (see K. P. Prussman, M. Weigner, M. B. Scheidegger, and P.Boesiger, “SENSE: sensitivity encoding for fast MRI,” Magn. Reson. Med.,vol. 42, pp. 952-962, 1999), have been developed and successfullydemonstrated in a number of applications. These two techniques and theirvariants provide faster imaging by using known arrays of receiver coils,but they also make use of the unique sensitivity profiles of elements ofa receiver array in order to complement the spatial encoding generallyaccomplished through repeated application of phase encoding magneticfield gradients.

As the number of array elements increases and their size continues todecrease, conductive losses become more dominant. These losses canoverwhelm any SNR gains expected from use of smaller coils that expressless body noise. The use of cryogenically cooled copper/HTS coils canextend the depth at which SNR gains can be achieved through phased arrayacquisition. The potential SNR gain using large arrays increases withthe number of elements: SNR gain goes up significantly when a singlecoil (N=1) is replaced with four coils (N=4), and it increases even morefor N=8 or N=16 arrays. Thus, the potential advantage of cryogenicallycooled//HTS receive arrays with a large number of elements becomes evengreater. These SNR gains can be used alongside parallel imaging toachieve higher accelerations while preserving maximum available imageSNR. Properly designed rf receiver coils are sensitive to rf magneticfields, while being substantially insensitive to rf electric fields.That is why an MRI coil is always designed to form a rf resonator.

Our invention includes designs of both superconducting single coilresonators and coil array resonators and hydride single coil and coilarray resonators. Superconducting coil in either surface coil or volumecoil configuration is formed out of four or more sections ofdielectric/superconductor or dielectric/metal strips. Strips are madeout of thin HTS or metal thin films deposited on dielectric rigid orflexible substrates. Such strips are connected together via in buildcapacitors. At each of the connection YBCO layers and separated themdielectric layer form a capacitor. Resonant frequency is determinedmainly by length of the structure and separating YBCO layers dielectricthickness and dielectric constant. Both surface flat, saddle coils andvolume birdcage coils were designed. Birdcage radiofrequency coils havebeen widely used in magnetic resonance imaging because of theirefficiency and azimuthal B1 field homogeneity and design of allsuperconducting birdcage for small animals has a practical potential. Inthe invention both single coil and phased array configurations aredescribed. In addition, an idea for multi-animal simultaneousmeasurement set up is shown for both flat and birdcage-likesuperconducting arrays. A small cryogenic system for cooling downsuperconducting coils is also shown.

Suitable Materials

Suitable dielectric material for use in this invention include, withoutlimitations, any dielectric material compatible with the superconductorsor metallic conductors used to fabricate the MRI coils or coil arrays ofthis invention. Exemplary examples include, without limitation, SiO₂,Si₃N₄, Al₂O₃, Y₂O₃, La₂O₃, Ta₂O₅, TiO₂, HfO₂, ZrO₂, or the like ormixture or combinations thereof.

Suitable superconducting material for use in this invention include,without limitations, any high temperature superconducting materialcapable of being deposited using well known thin film depositiontechniques. Preferred high temperature superconducting materialsinclude, without limitation, high temperature superconducting materialshaving a T_(c) above a temperature of liquid nitrogen or liquid carbondioxide. One preferred class of superconducting materials include,without limitations, high temperature cuperate superconductors.Exemplary examples of cuperate superconductors include, withoutlimitation, YBa₂Cu₃O₇, La_(2−x)Ba_(x)CuO₄, La_(2−x)Sr_(x)CuO₄,La_(2−x)Sr_(x)CaCuO₄, Bi₂Sr₂Ca₂Cu₃O₁₀, Tl₂Ba₂Ca₂Cu₃O₁₀,Hg_(0.8)Tl_(0.2)Ba₂Ca₂Cu₃O_(8.33), HgBa₂Ca₂Cu₃O₈, HgBa₂Ca₃Cu₄O₁₀₊,HgBa₂Ca_(1−x)Sr_(x)Cu₂O₆₊, HgBa₂CuO₄ ⁺, TlBa₂Ca₂Cu₃O₉₊, Tl₂Ba₂Ca₂Cu₃O₁₀,Tl_(1.6)Hg_(0.4)Ba₂Ca₂Cu₃O₁₀₊, Tl_(0.5)Pb_(0.5)Sr₂Ca₂Cu₃O₉,Tl₂Ba₂CaCu₂O₆, TlBa₂Ca₃Cu₄O₁₁, TlBa₂CaCu₂O₇₊, Tl₂Ba₂CuO₆,Bi_(1.6)Pb_(0.6)Sr₂Ca₂Sb_(0.1)Cu₃O_(y), Bi₂Sr₂Ca₂Cu₃O₁₀, Bi₂Sr₂CaCu₂O₉,Bi₂Sr₂Ca_(0.8)Y_(0.2)Cu₂O₈, Bi₂Sr₂CaCu₂O₈, AuBa₂Ca₃Cu₄O₁₁, AuBa₂(Y,Ca)Cu₂O₇, AuBa₂Ca₂Cu₃O₉, NdBa₂Cu₃O₇, GdBa₂Cu₃O₇, YBa₂Cu₃O₇, Y₂Ba₄Cu₇O₁₅,TmBa₂Cu₃O₇, YbBa₂Cu₃O₇, Sn₂Ba₂(Y_(0.5)Sr_(0.5))Cu₃O₈, La₂Ba₂CaCu₅O₉₊,(Sr, Ca)₅Cu₄O₁₀, Pb₂Sr₂(Y, Ca)Cu₃O₈, GaSr₂(Y, Ca)Cu₂O₇,(In_(0.3)Pb_(0.7))Sr₂(Ca_(0.8)Y_(0.2))Cu₂O_(x), (La, Sr, Ca)₃Cu₂O₆,La₂CaCu₂O₆₊, (Eu, Ce)₂(Ba, Eu)₂Cu₃O₁₀₊, (La_(1.85)Sr_(0.15))CuO₄,SrNdCuO, (La, Ba)₂CuO₄, (Nd, Sr, Ce)₂CuO₄, Pb₂(Sr, La)₂Cu₂O₆,(La_(1.85)Ba_(0.15))CuO₄, or the like, or mixtures or combinationsthereof.

Suitable metallic material for use in this invention include, withoutlimitations, copper, silver, gold, platinum, other noble metals, alloysthereof, or mixture or combinations thereof.

Fully Superconducting Coils

Referring now to FIGS. 1A-C, a preferred embodiment of a substantiallyrectangular, superconducting MRI coil or loop apparatus of thisinvention, generally 100, is shown to include four superconducting films102 deposited on four dielectric strips 104. The strips 104 are arrangedinto the substantially rectangular coil 100 so that the superconductingfilms 102 face each other at overlapping end portions 106. At the endportions 106, dielectric films 108 are interposed between facingsuperconducting film portions 110. The overlapping end portions 106 formbuilt in capacitors electronically interconnecting superconductinginductive portions 112 of the films 102.

Alternatively, looking at FIGS. 1D-F, another preferred embodiment of asuperconducting coil device of this invention, generally 100, is shownto include four superconducting films 102 deposited on four dielectricstrips 104. The strips 104 are arranged into the substantiallyrectangular coil 100 so that the superconducting films 102 face upforming built in capacitors at overlapping end portions 106, whichelectronically interconnect superconducting inductive portions 112 ofthe films 102.

Referring now to FIGS. 1G-H, a manufacturing process for forming theloops or coils of FIG. 1A-F is shown. A superconducting film ring 102 isdeposited onto a circular substrate 104. Then films of dielectric 114are deposited on top of portions 116 of the film 102. Then smallsuperconducting films 118 are deposited on top of the portions 120 ofthe dielectric films 114. The coils can be fabricated using, forexample, a multi-target pulsed laser deposition technique and standardphotolithography or ion milling.

One primary coil design parameter is the filling factor, which indicateshow much of the coil's shape is adjusted to accommodate a shape of abody for which the coil is intended. HTS technology, in principle,requires flat epitaxially polished dielectric substrates and as a resultsuch HTS MRI coils have different coil-body distances in the coil'scenter than at their edges. To overcome this deficiency, the apparatusesof the present invention are fabricated by depositing sections of HTSfilms on very thin flexible dielectric substrates. Such deposition ispossible using an ion beam assisted deposition technique or a variant ofion beam assisted deposition.

Referring now to FIGS. 1I-J, two constructions for attaching the coilsof this invention to the outside world are shown. Looking at FIG. 1I,one construction 150 includes a substrate 152 having deposited thereon afirst film 154 of superconducting material. Deposited on the top of thefilm 154 is a dielectric film 156. And deposited on the dielectric film156 is a second film 158 of superconducting material. The construction150 also includes a metal pad 160 having bonded thereto a wire 162 forcommunication with the an MRI instrument. Looking at FIG. 1J, anotherconstruction 164 includes a bottom film 166 of a superconductingmaterial, a top film 168 of a superconducting material and a dielectricfilm 170 interposed therebetween. The construction 164 also includes awire 172 bonded to the metal pad metal pad 174 deposited on the a topfilm 168.

Referring now to FIG. 1K, an electrical schematic 180 is shown that isthe electrical equivalent of the coils constructions of FIGS. 1A-H. Theschematic 180 includes four inductors 182 interconnected by fourcapacitors 184. Depending on the inductance of the inductors and thecapacitance of the capacitors, the coils forms a resonance circuit,which is capable of transmitting and receiving RF signals correspondingto resonances of magnetically active nuclei.

Fully Superconducting Curvilinear Coils

Referring now to FIG. 2A, a preferred embodiment of a saddle orcurvilinear loop or coil of this invention, generally 200, is shown toinclude two straight members 202, where each straight member 202comprises a superconductor film 204 deposited on a rigid dielectricsubstrate 206. The saddle coil 200 also includes two curved member 208,where each curved member 208 comprises a plurality of superconductingfilm sections 210 deposited on a flexible dielectric substrate 212. Thesaddle coil 200 also includes four capacitors 214 formed fromoverlapping regions 216 of the two straight members 202 and the twocurved members 208. At the overlapping regions 216, dielectric films 218are formed to separate an end portion 220 of the superconducting films204 from end superconducting film sections 222 of the curved members208. If the straight members 202 are flipped over, then the dielectricfilms 218 are not needed as was shown in FIGS. 1D-F. Of course,depending on the deposition technique used to form the superconductingfilms, the film could be formed without being formed of separatedsections, where each section is flat and not curves.

Birdcage-Type Resonator using Curvilinear Coils

Looking at FIG. 2B, a preferred embodiment of an animal MRI or birdcageapparatus 224 is shown to include two saddle coils 200 arranged in aclosed configuration forming an animal cavity 226. In such a closedconfiguration, the saddles 200 work either as a single coil or an arrayof two coils. Preferably, the superconductors are high temperaturesuperconductors such as a YBCO superconductors. However, any other hightemperature superconductor can be used as well. It should be recognizedthat the resonance frequency of the coils 200 are controlled by wellknown factors such as the dielectric used, the thickness of thesuperconducting and dielectric layers, the diameter of curvature to namea few and one of ordinary skill in the art can adjust these parametersto form coils having a desired shape and desired resonance frequency.

Fully Superconducting Birdcage-Type Resonators

Referring now to FIGS. 3A & B, another preferred embodiment of an allsuperconducting birdcage apparatus, generally 300, is shown to includeeight straight members or legs 302, where each straight member 302comprises an outer rigid dielectric substrate film 304, an innerdielectric film 306 and a superconductor film 308 interposedtherebetween. The birdcage 300 also includes four circular members 310,where each curved member 310 comprises a superconducting film 312deposited on a flexible dielectric substrate 314. As in the birdcage ofFIGS. 2A & B, the superconducting film 312 is preferably fabricated as aplurality of substantially flat section; however, as fabricationtechniques progress, the superconducting film 312 may eventually be of afabricated curvilinear form. The legs 302 and the circular members 310are configured to form a generally cylindrical animal cavity 316. Thelegs 302 and circular or arcuate members 310 overlap at first and secondoverlap regions 318 and 320, each overlap region 318 or 320 forms acapacitor interconnecting inductors formed by the superconducting films.This design forms a low-pass birdcage resonator. The flexible dielectricsubstrates are generally between about 30 and about 50 μm thick andformed of yttrium, strontium, zirconium dielectric or a sapphiredielectric film. The inner dielectric film is generally telfon, otherpolymers, silica titanate or similar dielectric materials.

Referring now to FIGS. 3C & D, another preferred embodiment of an allsuperconducting birdcage apparatus, generally 300, is shown to includefour straight members or legs 302, where each straight member 302comprises an outer rigid dielectric substrate film 304, an innerdielectric film 306 and a superconductor film 308 interposedtherebetween. The birdcage 300 also includes four circular or arcuatemembers 310, where each curved member 310 comprises a superconductingfilm 312 deposited on a flexible dielectric substrate 314. As in thebirdcage of FIGS. 2A & B, the superconducting film 312 is preferablyfabricated as a plurality of substantially flat section; however, asfabrication techniques progress, the superconducting film 312 mayeventually be of a fabricated curvilinear form. The legs 302 and thecircular members 310 are configured to form a generally cylindricalanimal cavity 316. The legs 302 and circular or arcuate members 310overlap at overlap regions 318, each overlap region 318 forms acapacitor interconnecting inductors formed by the superconducting filmsin the legs. The apparatus 300 also includes four arcuate sections 320interlaced with the legs 304, where the sections 320 form capacitorsinterconnecting inductor form by the arcuate members 310. The fourlegged apparatus forms a band-pass birdcage resonator, where thecapacitors are placed not only on the legs, but also on the ring. Thefour flat strips comprise a YBCO/substrate composite and the fourflexible strips comprises a YBCO/buffer-layer/flexible ZrO₂ composite toform a four legs band-pass birdcage resonator.

Hybrid Coils

In order to accommodate requirements for usually complicated shapes ofoptimized MRI coils as well as to allow relatively easy cooling of HTScoils, we have also designed hybrid (HTS/cooper) MRI coils or arrays.Referring now to FIGS. 4A & B, a preferred mixed superconducting-metalcoil of this invention, generally 400, is shown to include two copperblocks 402 and two legs 404, where each leg 404 includes a dielectricsubstrate layer 406 and a superconducting layer 408 deposited thereon.The blocks 402 are positioned at end portions 410 of the legs 404 withthe superconducting layer 408 of the legs 404 facing the copper blocks402. The coil 400 also includes dielectric strips 412 interposed betweenthe copper blocks 402 and end portions 414 the superconducting layer 408of the legs 404. The coil 400 also includes metal pads 416 formed on endportions 418 of the dielectric layers 406 of the legs 402. The copperblocks 402, dielectric strips 412 and the end portions 414 of thesuperconducting layers 408 combine to form built-in internal capacitorsinterconnecting the copper blocks 404 and the superconducting layers408. The end portions 414 of the superconducting layers 408, the endportions 418 of the dielectric layers 406, and the metal pads 416 formbuilt-in external capacitors.

Referring now to FIGS. 4C & D, another preferred mixedsuperconducting-metal coil of this invention, generally 400, is shown toinclude two copper blocks 402 and two legs 404, where each leg 404includes a dielectric substrate layer 406 and a superconducting layer408 deposited thereon. The blocks 402 are positioned at end portions 410of the legs 404 with the dielectric substrate layer 406 of the legs 404facing the copper blocks 402. The coil 400 also includes dielectricstrips 412 formed on end portions 414 the superconducting layer 408 ofthe legs 404 and metal tabs 416 formed on the dielectric strips 412. Thecopper blocks 402, end portions 418 of the dielectric layer 406, and theend portions 414 of the superconducting layers 408 combine to formbuilt-in internal capacitors interconnecting the copper blocks 404 andthe superconducting layers 408. The end portions 414 of thesuperconducting layers 408, the dielectric strips 412, and the metaltabs 416 form built-in external capacitors.

The main concept of these mixed or composite coils are the same as inthe fully superconducting coils of FIGS. 1A-F; however, two sections ofthe HTS films are replaced with copper blocks allowing the coils to bedirectly cooled by a cooling system, i.e., the copper or other metallicblocks can be placed in direct contract with a cooled surface. As withthe fully superconducting coils, the mixed or composited coils of FIGS.4A-D include built in capacitors using two conducting layers separatedby a dielectric layer.

Referring now to FIG. 4E an equivalent circuit generally 450 is shownthat corresponds to the coils of FIGS. 4A-D. The circuit 450 includesinductors 452 interconnected by internal capacitors 454 and capacitivelyisolated from external electronic components by external capacitors 456.The circuit 450 also includes a virtual ground plane 458.

The hybrid MRI resonators of this invention include two sections ofYBCO/substrate and two pieces of copper which are interconnected via thebuilt-in internal capacitors 454. Two of the metal pads 416 are adaptedto couple the resonator to a scanner amplifier, while the other twometal pads 416 are adapted to decouple adjacent resonators if theindividual coils are used in an array configuration. Two ways ofcreating capacitors are shown. As shown in FIGS. 4A & B, the built-ininternal capacitors 454 comprise the copper block 402/the dielectricstrip 412/the superconducting layer 408 such as a YBCO layer. As shownin FIGS. 4C & D, the built-in internal capacitors 454 comprise thecopper block 402/the dielectric substrate layer 406/the superconductinglayer 408 such as a YBCO layer. The built-in internal capacitors 454 inconjunction with the conductive elements which for the inductors 452 forthe coil resonator, while the built-in external capacitors 456interconnect metal and superconducting films into single loop(resonator). The external capacitors 456 are designed to either connectthe resonator to an amplifier or for decoupling array elements.

Birdcage-Type Resonators using Hybrid Coils

Referring now to FIGS. 5A & B, a preferred embodiment of a mixedsuperconducting-metal birdcage array resonator, generally 500, is shownto include twelve hybrid coils 502 as shown in FIGS. 4A & B arranging ina circular configuration forming a cavity 504. In the coils 502, thecopper blocks 402 include a portion 506 that extends out past the coilslayers 406, 408, 412, and 416. The portions 506 are designed to directlycontact a cold inner surface 508 of a metal ring 510 that would be incontact with a coolant on its outer surface 512. The resonator 500 formsa cylinder having a cavity into which a small animal can be placed andthe assembly then placed in an MRI device. The resonator 500 is cooledby bring the outer surface of the metal ring 510 in contact with acoolant, such as liquid nitrogen. The resonator 500 is an example ofphased array made out of hybrid (metal/superconductor) resonators ofFIGS. 4A-D. The individual coils 502 can be mutually de-coupled, as itis required for phased array use via the built-in capacitors and wiresleading from the metal pads from one coil to the next or from a coil toa pre-amplifier or amplifier associated with the MRI device. Although anouter metal ring, preferably a copper ring, is shown in FIG. 5B, thering can be constructed out of any good heat conductor, metal ornon-metal. Preferred non-metal rings can be made out of polycrystallinesapphire or other non-metal thermal conducting materials.

Referring now to FIGS. 5C & D, another preferred embodiment of a mixedsuperconducting-metal birdcage array resonator, generally 550, is shownto include two thermal conducing members 552 (only one shown), eachmember 552 including a circular aperture 554 therethrough having twelveequally spaced, circularly configured protrusions 556 extending into theaperture 554. On each lateral side 558 of each protrusion 556 are placedlegs 560 extending between the two members 552 to form an elongateresonator where the aperture 554 comprises the small animal cavity.Looking from the protrusions 556 out, each leg 560 includes an inner,rigid dielectric substrate layer 562 in contact with a side 558 of aprotrusion 556 and a superconducting layer 564. These two layer 562 and564 extend between the two member 552. Each leg 560 also includes adielectric strip 566 formed on or in contact with an end portion 568 ofthe superconducting layer 564. Each dielectric strip 566 in turn hasdeposited thereon or is in contact with a metal pad 570. The metal pads570 can have a wire 572 bonded thereto by a soldier bump 574 so that theindividual coils can be formed into an array and/or connected topre-amplifiers or amplifiers associated with the MRI device. Theresonator 550 can also include climps 576 designed to hold the two legs560 per protrusion against the protrusions 556. The member 552 aredesigned to directly contact a coolant on their outer surfaces 578. Theresonator 550 forms a cylinder having a cavity into which a small animalcan be placed and the assembly then placed in an MRI device. Theresonator 550 is cooled by bring the outer surfaces 578 of the members552 in contact with a coolant, such as liquid nitrogen. The resonator550 is an example of phased array made out of hybrid(metal/superconductor) coils. The individual coils 502 can be mutuallyde-coupled, as it is required for phased array use via the built-incapacitors and wires leading from the metal pads from one coil to thenext or from a coil to a pre-amplifier or amplifier associated with theMRI device. The members 552 are preferably made out of copper, but othermetal will work, especially metals having a high thermal and electricconductivities.

Referring now to FIG. 5E, a schematic corresponding to the hybrid arraysof FIGS. 5A-D is shown to include the coil capacitors C and coilinductors L along with coupling, decoupling, tuning and matchingelements CC, DC and CM. The outputs O/P are forwarded to preamps thatcan be either within the cooled area or external thereto. The coupling,decoupling, tuning and matching elements can be similarly applied to anyarray of MRI coils of this inventor or to any single MRI coil of thisinvention.

Referring now to FIGS. 6A & B, another preferred embodiment of a mixedsuperconducting-metal birdcage resonator of this invention, generally600, is shown to include a metallic tube 602 having formed on an outersurface 604 of the tube 602 two curvilinear superconducting layers 606and two straight superconducting layers 608. The curvilinear layers 606are disposed radially across end portions 610 of the tube 602, while thestraight layers 608 run axially from end portions 612 of the curvilinearlayers 608. At their overlapping regions 614 and 616, a layer 618 ofmica or other dielectric material is interposed therebetween. Theseoverlapping regions form built-in capacitors interconnecting inductiveelements formed by the non-overlapping 620 of the superconducting layers606 and 608.

Referring now to FIGS. 7A & B, another preferred embodiment of a mixedsuperconducting-metal birdcage array resonator, generally 700, is shownto include two metallic rings 702 and two straight superconducting legs704 connecting the rings 702 at opposite sides of each ring 702 atflattened sections 706 with a dielectric layer 707 interposed betweenthe flattened section 706 of the rings 702 and overlapping portions 708of the legs 704.

In FIGS. 6A & B and 7A & B, the dielectric layer or mica layer isgenerally about 20 μm thick. The ring or tube is generally about 10 mmthick and about 2″ long and about 2.5″ in diameter. The resonatorsresonate at a frequency of about 200 MHz. Of course, the resonatefrequency can be changed by changing the capacitance of the built-incapacitors and the inductance of the inductive regions of thesuperconducting layer and metallic layers.

Referring now to FIGS. 8A & B, a preferred small animal MRI resonatorapparatus, generally 800, is shown to include a plastic or non-magneticcryostat housing 802 having a cylindrical aperture 804 therethroughdefining a small animal cavity. Surrounding the aperture 804, is acylindrical MRI resonator 806 of this invention in thermal contact witha thermally conductive plate 808. The plate 808 comprises the outersurface of a liquid nitrogen reservoir 810. The housing 802 alsoincludes a ring sealing member 812 having two electrical feed tube 814extending therethrough. The housing 802 is capable of being placed undera vacuum. The cryostat 800 includes a vacuum shroud 802, a liquidnitrogen container 810 with one side wall made out of a sapphire plate808. The container 810 includes a liquid nitrogen inlet 816 and a liquidnitrogen outlet 818. The plate temperature will be uniformly at 77K andwill not dependent on level of liquid nitrogen in the container 810. TheMRI resonator 806 comprises copper and/or YBCO materials and will be inthermal contact with the plate 808. In this apparatus 800, the aperture804 can either extend the entire length of the housing or it can stop atthe plate 808 so that the small animal is confined within the part ofthe apparatus 800 surrounded by the resonator 806.

Referring now to FIG. 9, another preferred small animal MRI resonatorapparatus, generally 900, is shown to include four hybrid array 902 ofFIGS. 5A-D each array 902 defining having a small animal cavity 904. Thefour arrays 902 are housed in a vacuum shroud or housing 906 and are inthermal contact with a plate 908 which forms an outer surface of aliquid nitrogen reservoir (not shown). The housing 906 includes a top(not shown) that seals the housing 906 so that the interior can beevacuated, where the top includes electrical wiring feed throughs asdescribed previously. The apparatus 900 can accommodate up to fouranimals and MRI data can be acquired on each simultaneously orseparately.

Referring now to FIG. 10, another preferred small animal MRI resonatorapparatus, generally 1000, is shown to include a non-conductive housing1002 having four small animal tubes 1004. The housing 1002 also includeseight flat MRI coil or MRI array apparatuses 1006, where each tube 1004is adjacent three MRI apparatuses 1006. The eight MRI apparatuses 1006are in thermal contact with a thermally conducting plate 1008 whichforms an outer surface of a liquid nitrogen reservoir (not shown). Thehousing 1002 includes a top (not shown) that seals the housing 1002 sothat the interior can be evacuated, where the top includes electricalwiring feed throughs as described previously. The apparatus 1000 canaccommodate up to four animals and MRI data can be acquired on eachsimultaneously or separately. The rigid flat MRI apparatuses 1006comprise preferably HTS coils and by sharing coils, a reduced number ofHTS coils are needed for such systems. Each tube in which a mouse isplaced is surrounded by array of superconducting coils.

Referring now to FIGS. 11A-D, illustrate the physical characteristic soMRI coils and arrays made thereform. Looking at FIGS. 11A & B, themagnetic fields generated by the coils of this invention are shown.Looking at FIGS. 11 C & D, the SNR for these coils is shown.

The inventors have found that when tuning and matching circuitry isplaced next to the superconducting array and cooled together with thearray, the entire system has superior performance. In fact, cooling thetwo circuit elements together is preferred because it allow us to takeadvantage of the high Q of the arrays of this invention. The inventorshave also found that by integrating a pre-amplifier into this circuitryso that the pre-amp is cooled as well results in further noisereduction. Looking at FIGS. 12A & B, the performance of a circuit havingthe tuning and matching circuitry within the small animal device andcooled simultaneously produces improved SNR. FIG. 12B also shows thetuning and matching circuitry for a coil similar to the coils of thisinvention disclosed in PCT application Ser. No. PCT/US03/33933, filed 24Oct. 2003, published as WO04038431, incorporated herein by reference.The tuning and matching circuitry shown in FIG. 12B can be use with thecoils and arrays of this invention as well. Co-cooling the matching andtuning circuitry, applies, in general, not only to thin film arrays, butalso to saddle, birdcage and hybrid coils/arrays. In fact, we haveinstalled such low temperature circuit in our cryostat, which designingidea is presented in the provisional.

All references cited herein are incorporated by reference. While thisinvention has been described fully and completely, it should beunderstood that, within the scope of the appended claims, the inventioncould be practiced otherwise than specifically described. Although theinvention has been disclosed with reference to its preferredembodiments, from reading this description those of skill in the art canappreciate changes and modifications that may be made which do notdepart from the scope and spirit of the invention as described above andclaimed hereafter.

1. An MRI apparatus capable of imaging small nonhuman animalscomprising: a vacuum housing including at least one aperture, where eachaperture is configured to receive a small nonhuman animal, a coolantassembly including a coolant inlet, a coolant outlet and a cold plate,where a coolant is configured to cool the cold plate, at least oneresonator, each resonator comprising: two closed saddle-shaped coils inthermal contact with the cold plate, each saddle-shaped coil comprising:four members, each member including a superconducting layer, where themembers are arranged in order to form four overlapping regions, eachoverlapping region comprises:  a capacitor formed from overlappingportions of the superconducting layers of two of the members and anoverlapping region dielectric layer interposed therebetween, where twoof the members are straight and two of the members are curvilinear inorder to form the closed saddle-shaped coils, and where a resonatorsurrounds each at least one aperture.
 2. The apparatus of claim 1,wherein each member further comprises: a substrate dielectric layer uponwhich the superconducting layer was formed, where the dielectric layerof the straight members comprise a rigid dielectric material and thedielectric layer of the curvilinear members comprise a flexibledielectric material.
 3. The apparatus of claim 1, wherein thesuperconducting layer of the curvilinear members comprise a plurality ofsubstantially flat superconducting segments.
 4. The apparatus of claim3, wherein the overlapping regions of the superconducting layer of thecurvilinear member comprise one of the substantially flatsuperconducting segments.
 5. The apparatus of claim 1, wherein theoverlapping region dielectric layers comprise separate dielectric layersdistinct from the substrate dielectric layers.
 6. The apparatus of claim5, wherein the substrate and the overlapping region dielectric layersare composed of the same or different dielectric material.
 7. Theapparatus of claim 1, wherein the overlapping region dielectric layerscomprise portions of the substrate dielectric layers of the members. 8.The apparatus of claim 1, wherein each coil apparatus includes: a metallayer formed on an exposed portion of a dielectric layer or an externaldielectric layer formed on an exposed portion of a superconducting layerwith a metal layer formed on the outer surface of the externaldielectric layer, where the metal layer forms a coupling or decouplingcapacitive element with a corresponding portion of the superconductinglayer.
 9. The apparatus of claim 8, each coil apparatus furtherincludes: a wire bonded to the metal layer, where the wire links aplurality of the apparatuses together to form an array or to connect theapparatus to a pre-amplifier.
 10. The apparatus of claim 1, furthercomprising: a plurality of separated spaced apart apertures, eachconfigured to receive a small nonhuman animal allowing the MRI apparatusto simultaneously receive and image a plurality of animals with MRI. 11.An MRI apparatus capable of simultaneously imaging at least two smallnonhuman animals comprising: a vacuum housing including at least twosingle-sided, non-collinear apertures, each aperture configured toreceive a small nonhuman animal allowing the MRI apparatus tosimultaneously receive a plurality of small nonhuman animals, a coolantassembly including a coolant inlet, a coolant outlet and a cold plate,where a coolant is configured to cool the cold plate, at least tworesonators comprising: a plurality of closed saddle-shaped coils inthermal contact with the cold plate and arranged in order to form acylindrical structure, where a resonator surrounds each aperture, andwhere the MRI apparatus is capable of simultaneously imaging a smallnonhuman animal placed in each of the at least two single-sided,non-collinear apertures with MRI.
 12. The apparatus of claim 11, whereinthe at least two resonators also comprise: two closed saddle-shapedcoils.
 13. The apparatus of claim 12, wherein each closed saddle-shapedcoil comprises: four members, each member including a superconductinglayer, where the members are arranged in order to form four overlappingregions, where each overlapping region comprises a capacitor formed fromoverlapping portions of the superconducting layers of two of the membersand an overlapping region dielectric layer interposed therebetween,where two of the members are straight and two of the members arecurvilinear in order to form the closed saddle-shaped coils.
 14. Theapparatus of claim 13, wherein each member further comprises: asubstrate dielectric layer upon which the superconducting layer wasformed, where the dielectric layer of the straight members comprise arigid dielectric material and the dielectric layer of the curvilinearmembers comprise a flexible dielectric material.
 15. The apparatus ofclaim 13, wherein the superconducting layer of the curvilinear memberscomprise a plurality of substantially flat superconducting segments. 16.The apparatus of claim 15, wherein the overlapping regions of thesuperconducting layer of the curvilinear member comprise one of thesubstantially flat superconducting segments.
 17. The apparatus of claim13, wherein the overlapping region dielectric layers comprise separatedielectric layers distinct from the substrate dielectric layers.
 18. Theapparatus of claim 17, wherein the substrate and the overlapping regiondielectric layers are composed of the same or different dielectricmaterial.
 19. The apparatus of claim 13, wherein the overlapping regiondielectric layers comprise portions of the substrate dielectric layersof the members.
 20. The apparatus of claim 13, wherein each coilapparatus includes: a metal layer formed on an exposed portion of adielectric layer or an external dielectric layer formed on an exposedportion of a superconducting layer with a metal layer formed on theouter surface of the external dielectric layer, where the metal layerforms a coupling or decoupling capacitive element with a correspondingportion of the superconducting layer.
 21. The apparatus of claim 20,each coil apparatus further includes: a wire bonded to the metal layer,where the wire links a plurality of the apparatuses together in order toform an array or in order to connect the apparatus to a pre-amplifier.22. An MRI apparatus capable of simultaneously imaging at least twosmall nonhuman animals comprising: a vacuum housing including aplurality of separated spaced apart apertures, each aperture configuredto receive an animal allowing the apparatus to simultaneously receive aplurality of small nonhuman animals, a coolant assembly including acoolant inlet, a coolant outlet and a cold plate, where a coolant isconfigured to cool the cold plate, at least two resonators comprising: aplurality of closed saddle-shaped coils in thermal contact with the coldplate and arranged in order to form a cylindrical structure, where aresonator surrounds each aperture, and where the MRI apparatus iscapable of simultaneously imaging a small nonhuman animal placed in eachof the plurality of separated spaced apart apertures with MRI.
 23. Theapparatus of claim 22, wherein the at least two resonators alsocomprise: two closed saddle-shaped coils.
 24. apparatus of claim 22,wherein each closed saddle-shaped coil comprises: four members, eachmember including a superconducting layer, where the members are arrangedin order to form four overlapping regions, where each overlapping regioncomprises a capacitor formed from overlapping portions of thesuperconducting layers of two of the members and an overlapping regiondielectric layer interposed therebetween, where two of the members arestraight and two of the members are curvilinear in order to form theclosed saddle-shaped coils.
 25. The apparatus of claim 24, wherein eachmember further comprises: a substrate dielectric layer upon which thesuperconducting layer was formed, where the dielectric layer of thestraight members comprise a rigid dielectric material and the dielectriclayer of the curvilinear members comprise a flexible dielectricmaterial.
 26. The apparatus of claim 24, wherein the superconductinglayer of the curvilinear members comprise a plurality of substantiallyflat superconducting segments.
 27. The apparatus of claim 26, whereinthe overlapping regions of the superconducting layer of the curvilinearmember comprise one of the substantially flat superconducting segments.28. The apparatus of claim 24, wherein the overlapping region dielectriclayers comprise separate dielectric layers distinct from the substratedielectric layers.
 29. The apparatus of claim 28, wherein the substrateand the overlapping region dielectric layers are composed of the same ordifferent dielectric material.
 30. The apparatus of claim 24, whereinthe overlapping region dielectric layers comprise portions of thesubstrate dielectric layers of the members.
 31. The apparatus of claim24, wherein each coil apparatus includes: a metal layer formed on anexposed portion of a dielectric layer or an external dielectric layerformed on an exposed portion of a superconducting layer with a metallayer formed on the outer surface of the external dielectric layer,where the metal layer forms a coupling or decoupling capacitive elementwith a corresponding portion of the superconducting layer.
 32. Theapparatus of claim 31,each coil apparatus further includes: a wirebonded to the metal layer, where the wire links a plurality of theapparatuses together in order to form an array or in order to connectthe apparatus to a pre-amplifier.